R99 renewable diesel holds much less dissolved water than FAME biodiesel. Mixing these fuels changes how the finished blend handles water, cold temperatures, and storage.

Commercially formulated blends can perform well when they meet fuel specifications and engine requirements. However, mixing unknown fuels in a storage tank can create an unpredictable product—and blending should never be used as a substitute for removing water.

R99 and FAME Are Different Fuels

R99 renewable diesel is a hydrocarbon fuel commonly manufactured by hydrotreating renewable feedstocks. Its chemistry resembles petroleum diesel.

FAME—fatty acid methyl esters—is conventional biodiesel. It has a different chemical structure and is commonly sold in blends such as B5 or B20. B20 contains 20% FAME biodiesel; the remaining portion can include petroleum diesel or renewable diesel.

The U.S. Department of Energy distinguishes renewable diesel, which meets ASTM D975, from biodiesel blendstock, which meets ASTM D6751. The finished blend must meet the applicable specification.

Which Fuel Holds More Water?

FAME holds substantially more dissolved water than R99 at the same temperature. As FAME content increases, the blend generally gains the ability to keep more water dissolved.

One NREL study measured water-saturation values of approximately 85 ppm for the tested renewable diesel and 1,567 ppm for the tested B100 FAME. These are examples from specific samples, not universal limits. Fuel composition and temperature affect the actual saturation point.

Greater water-holding capacity does not mean better fuel quality. It means more water can remain present without forming a visible layer.

Clear Fuel Can Still Contain Water

Water occurs in fuel in three forms:

• Dissolved water: Water distributed at the molecular level. The fuel may look clear.
• Suspended or emulsified water: Small droplets dispersed through the fuel, sometimes producing haze.
• Free water: Separated water that typically collects at the tank bottom.

A Karl Fischer test measures water in the tested sample. It does not, by itself, identify how much was dissolved and how much was present as droplets. Representative sampling is essential.

For example, 225 ppm by weight equals 0.0225% water. That result alone does not establish the FAME percentage, prove that all water is dissolved, or determine whether the fuel meets every applicable requirement.

Why Avoid Uncontrolled Blending?

1. Water Can Separate After Mixing

When a FAME-containing fuel is diluted with R99, the resulting blend may hold less dissolved water than the original fuel. If the water content exceeds the new blend’s saturation limit, some water can separate into droplets.

Cooling can also reduce water solubility. Fuel that appears clear during delivery may develop water haze or separated water after conditions change.

This separation is not inevitable. It depends on the starting water content, temperature, and final composition.

2. Adding FAME Does Not Remove Water

Adding FAME may allow more water to remain dissolved. The fuel could appear clearer while still containing the same water.

Making water less visible is not water removal. Adding dry fuel can lower the measured concentration through dilution, but it does not extract the water already in the tank.

3. Cold-Weather Performance Can Change

Adding FAME to a suitable winter-grade R99 can raise the blend’s cloud point. Depending on the feedstock and concentration, crystals may form at temperatures where the original R99 would remain usable.

The cold-weather performance of the finished mixture must be established rather than assumed from either component.

4. Storage Stability Can Change

FAME can reduce a blend’s resistance to oxidation. As fuel ages, oxidation can contribute to acids, gums, and deposits.

This matters for standby generators and other equipment where fuel remains in storage for extended periods. Mixing a fresh delivery with old fuel does not establish that the resulting mixture is suitable for continued storage.

5. The Final Blend May Exceed Equipment Requirements

FAME can improve lubricity, but it also changes density, viscosity, and evaporation characteristics. These changes become more significant at higher blend levels.

An engine approved for R99 is not automatically approved for every R99/FAME mixture. Confirm the allowable biodiesel percentage and finished-fuel requirements with the equipment manufacturer.

Can Fuel Polishing Fix the Problem?

Fuel polishing can remove solids and, with suitable equipment, free and dispersed water. Ordinary particle filtration, settling, and centrifuging do not directly remove truly dissolved water.

Reducing dissolved water requires an appropriate drying process, such as fuel-compatible vacuum dehydration or a properly selected adsorbent system. Polishing also cannot reverse chemical degradation caused by oxidation.

Water-block filters serve a different purpose. Cim-Tek describes Hydrosorb primarily as a water-alert filter that restricts flow when excess water is detected. It should not be assumed to dry fuel to a specified ppm level.

Know What Is Going Into Your Tank

Before combining deliveries, confirm the fuel type, FAME percentage, water condition, and equipment requirements. Check a separate tank-bottom sample for accumulated water, and use laboratory testing when precise measurements are needed.

Avoid blending unknown fuels to correct contamination. Identify the problem, remove the contamination, and verify the finished fuel. A controlled, documented blend is different from mixing whatever fuel happens to be available.

Dieselcraft helps operators assess contamination and select practical fuel-testing and polishing equipment.

Call 530-613-2150 or visit dieselcraft.com.

The post R99 vs. Biodiesel Blends: Water Retention, Blending Risks & Fuel Care | Dieselcraft appeared first on Dieselcraft.

1. Emulsifiers / Dispersants (“Water Removers”)

These break water into microscopic droplets and suspend them in the fuel. The water then passes through the system and is burned off as vapor.

Pros: Good for small amounts of water, prevents icing, avoids visible free water.

Cons: Doesn’t eliminate water—just sends it to the engine. Too much can cause wear or corrosion. Not ideal for modern high‑pressure systems.

2. Demulsifiers (Preferred for Storage Tanks)

These cause water droplets to combine and settle at the bottom as free water.

Pros: Enables true removal via drains, separators, or polishing. Reduces corrosion and microbial growth.

Cons: Requires a way to physically remove the separated water.

Key Points

•             No additive destroys or converts water; claims otherwise are marketing.

•             Best practice: Use demulsifiers + mechanical removal (drains, separators, polishing).

•             For stored diesel: choose demulsifiers and remove water regularly; avoid strong emulsifiers in bulk tanks without drainage

MORE INFORMATION

The post Why Chemical Fuel Additives Don’t Remove Water from Diesel appeared first on Dieselcraft.

Fuel polishing and fuel maintenance are related concepts in the context of stored fuels (especially diesel), but they differ in scope, frequency, and approach. These terms are most commonly used for backup generators, marine vessels, emergency power systems, or any application where fuel sits in tanks for long periods and can degrade.

What is Fuel Polishing?

Fuel polishing is a specific, targeted process (often a one-time or periodic service) that involves recirculating (or “polishing”) the fuel through a multi-stage filtration system to remove contaminants. It typically includes:

• Drawing fuel from the bottom of the tank (where water, sludge, sediment, and microbial growth—”diesel bugs”—accumulate).
• Passing it through progressive filters (e.g., coarse to fine, often down to 4 microns or better), water separators, and sometimes coalescers.
• Returning the cleaned fuel to the top of the tank to avoid remixing contaminants.
• The goal is to restore the fuel to meet standards like ASTM D975 (for diesel) by removing water, particulates, microbial biomass, and sometimes reversing oxidation effects.

It’s essentially an advanced cleaning/filtration procedure to salvage contaminated fuel without replacing it. It’s proactive or corrective, often done when fuel has degraded (e.g., dark color, sludge buildup) or as scheduled maintenance (e.g., annually for standby tanks). It’s cheaper, greener, and less disruptive than dumping and replacing the fuel.

What is Fuel Maintenance?

Fuel maintenance is the broader, ongoing program or strategy to keep stored fuel in good condition over time. It encompasses multiple practices to prevent degradation, including:

• Regular fuel polishing (as one key component).
• Fuel testing and sampling (e.g., checking for water, microbes, clarity).
• Adding stabilizers, biocides, or conditioners to prevent oxidation and microbial growth.
• Tank inspections, water draining, filter changes.
• Proper tank design/venting to minimize condensation.
• Monitoring usage and turnover (fresh fuel helps, as does avoiding long stagnation).

In many sources, fuel polishing is described as part of a fuel maintenance program—especially for long-term stored diesel in generators or boats. A good fuel maintenance plan might include periodic polishing sessions, but also preventive steps to reduce how often heavy polishing is needed.

The post What is the difference between Fuel Polishing and Fuel Maintenance? appeared first on Dieselcraft.

1. Corrosion and Rust Water speeds up oxidation on metal surfaces (tanks, lines, pumps, injectors), forming rust. Rust particles become abrasive contaminants that accelerate wear throughout the system.
2. Microbial Growth (“Diesel Bug”) Bacteria, fungi, and yeasts flourish at the water-fuel interface in the tank bottom. They consume diesel hydrocarbons, multiply rapidly, produce acidic byproducts (further corroding components), and form slimy biomass/sludge. This clogs filters and lines, while dead microbes add more particulates.
3. Loss of Lubricity and Increased Wear Diesel provides natural lubrication for high-pressure fuel pumps and injectors. Water dilutes this lubricity, leading to friction, scoring, erosion, cavitation (pitting), spalling, and premature failure—especially in modern common-rail systems.
4. Engine Performance and Combustion Issues
   • Hard starting, rough idling, misfires, stalling, or complete shutdowns (water doesn’t combust properly).
   • Power loss, poor acceleration, reduced fuel efficiency, and higher emissions.
   • In severe cases: Hydro-lock (water in cylinders), injector tip explosion, pump cavitation, or catastrophic damage.
5. Filter Clogging and System Blockages Sludge, biomass, rust, and particulates quickly plug fuel filters, restricting flow and starving the engine of fuel—often leading to sudden failures.
6. Long-Term and Costly Consequences Accelerated wear shortens engine/component life, skyrockets maintenance and repair expenses (e.g., injector or high-pressure pump replacements can run thousands of dollars), and increases downtime risks.

In essence, water doesn’t just sit harmlessly—it creates a snowball effect of degradation, especially in stored, standby, or infrequently used systems (generators, marine vessels, backup tanks, etc.). Prevention is key: Regular fuel maintenance—including water testing, stabilizers/biocides (used judiciously), effective water separators, good tank hygiene, and periodic polishing with tools like your purifier product—removes water early, stabilizes the fuel, and avoids most issues.

https://dieselcraft.com/portable-fuel-polishing/

The post Problems Caused by Water in Diesel Fuel and How to Prevent Them appeared first on Dieselcraft.

Water enters diesel in three primary forms:

• Dissolved (invisible, fully in solution within the fuel).
• Emulsified (tiny suspended droplets that make the fuel appear cloudy or hazy).
• Free (separate liquid layer that settles at the tank bottom, since water is denser than diesel).

Main Sources of Water Contamination

Human Error or Poor Handling Practices Simple oversights like leaving fill caps unsecured, exposing drums or portable tanks to rain, improper storage, or careless refueling can allow direct water entry.

Condensation (by far the most common source) Temperature fluctuations cause fuel tanks to “breathe.” As the fuel and tank cool (e.g., overnight, during seasonal changes, or in varying weather), warm, humid air is drawn in through vents, breathers, or fill pipes. This air cools upon contact with the colder tank walls or fuel surface, reaching its dew point and condensing into liquid water droplets. These droplets accumulate and mix into the fuel. This process is exacerbated in:

Above-ground tanks (greater temperature swings).

Partially filled tanks (larger air space and surface area).

Humid climates or environments with high day-night temperature variations.

Contaminated Fuel from the Supply Chain or Delivery Water can already be present when you receive the fuel. Causes include:

Insufficient settling time at the refinery or during transport.

Shared pipelines or transport systems that introduce moisture.

Contaminated supplier storage tanks. Excess dissolved water may exceed saturation (especially as fuel cools), causing it to “fall out” as free water that settles in your tank.

Leaks or Compromised Tank Integrity External water enters through:

Damaged seals, cracked tanks, faulty vents, loose fill caps, or degraded spill containment.

Rain, snow, pressure washing, groundwater seepage, flooding, or even accidental drainage of collected rainwater into the tank.

Need help? See https://dieselcraft.com/portable-fuel-polishing/

The post How Water Gets Into Diesel appeared first on Dieselcraft.

When biodiesel is poorly made—often referred to as “bad biodiesel”—one of the biggest red flags is a high concentration of glycerine (or glycerin/glycerol). Here’s why that matters:
What Glycerine Is in Biodiesel
• Glycerine is a byproduct of the transesterification process used to make biodiesel from fats or oils.
• Ideally, it should be separated and removed during production.
• If not properly removed, it remains in the fuel as free glycerine or bound glycerides (mono-, di-, or triglycerides).
Why High Glycerine Is a Problem
• Engine Damage: Excess glycerine can clog fuel injectors, form deposits on pistons and valves, and lead to poor combustion.
• Cold Weather Issues: Glycerine solidifies at relatively high temperatures, which can cause fuel gelling and blockages in cold climates.
• Storage Instability: Glycerine can separate out over time, reducing shelf life and causing sediment in tanks.
• Fails Standards: High glycerine levels mean the fuel doesn’t meet ASTM D6751 or EN 14214 standards, making it unsuitable for commercial use.
How It’s Measured
• Standards like ASTM D6584 and EN 14105 use gas chromatography to measure both free and total glycerine in biodiesel.
• Acceptable limits are very low—typically <0.02% for free glycerine and <0.24% for total glycerine in B100 biodiesel.
Can It Be Fixed?
• Yes, but it requires reprocessing or purification, such as:
• Washing the biodiesel to remove impurities
• Vacuum distillation
• Membrane filtration or electrodialysis for crude glycerine recovery
Contact www.dieselcraft.com for a fuel purifier and centrifuge to fix the problem.

MORE INFO

The post Black or Brown Solids in My Diesel Fuel: Causes and Solutions appeared first on Dieselcraft.

The Importance of Fuel Maintenance

The fuel that powers these emergency generators is just as crucial as the generators themselves. Over time, fuel can degrade due to microbial contamination, water accumulation, sediment buildup, and natural aging. If left unchecked, this deterioration can lead to generator failure when it is needed most.

Poor fuel maintenance can cause clogged filters, damaged injectors, corroded fuel systems, and reduced generator performance. In the worst-case scenario, fuel contamination may result in complete generator failure during a critical emergency.

Advantages of Fixed Fuel Polishing Systems

To counter these risks, many hospitals have adopted fixed fuel polishing systems. These systems clean and filter stored fuel, removing contaminants and water to maintain its integrity. The benefits of fuel polishing systems include:

1. Enhanced Reliability: Ensures fuel remains in optimal condition, reducing the risk of generator failure.
2. Extended Equipment Lifespan: Prevents damage caused by degraded fuel, prolonging the life of both the fuel and the generator.
3. Cost Efficiency: Reduces maintenance expenses, prevents costly generator repairs, and extends fuel usability.
4. Regulatory Compliance: Helps hospitals meet fuel maintenance regulations, avoiding potential penalties and ensuring operational readiness.

Risks of Ignoring Fuel Maintenance

Neglecting fuel care can lead to significant consequences, including:

1. Unreliable Backup Power: Degraded fuel increases the risk of generator malfunction or total failure.
2. Higher Operational Costs: Poor fuel management results in expensive repairs, equipment replacement, and potential fines for non-compliance.
3. Patient Safety Hazards: A power failure in a hospital can have life-threatening consequences if essential medical equipment becomes inoperable.

Ensuring Reliable Emergency Power

Proper fuel management requires routine testing, monitoring, and maintenance to ensure high fuel quality and availability. Hospitals must implement robust fuel management protocols to safeguard their critical infrastructure, minimize financial risks, and, most importantly, protect patient lives. In times of crisis, having a well-maintained fuel system can make the difference between seamless medical care and a catastrophic power failure. MORE INFO

The post The Vital Role of Generator Fuel in Hospitals appeared first on Dieselcraft.

Here are the key questions to investigate:

• Is the fuel clear and bright or cloudy?
• Are you using an additive? If so, which one, at what ratio, and how often?
• Is the entire fuel volume cloudy, or only the bottom around the fuel pick-up?

Fuel Sampling Steps

1. Take a sample from the water separator. Is the fuel clear and bright, or cloudy?
2. Take a sample from the top of the fuel tank. Is it clear and bright, or cloudy?
3. Take a sample from the next fuel delivery. Is it clear and bright, or cloudy?

Checking for Overdosing Issues

• Is your supplier providing a winter blend fuel?
• Is the supplier blending the additive? If so, ask for the exact ratio.
• If the fuel supplier overdosed the fuel—or if you added a cold flow improver to an already treated winter blend—you may have caused the issue.
• Water reacts to excessive additives, preventing it from being trapped by a water-blocking filter.

Understanding Additive Ratios

It’s crucial to use the correct amount of additive:

• There are 128 ounces in 1 gallon.
• If an additive treats 1 gallon per 1,000 gallons of fuel, then 1 ounce treats 7.8 gallons.
• Did you add more than the recommended amount? More is not better!

Locating and Removing the Problem Fuel

• Overdosed additives tend to sink to the tank bottom, where the engine’s fuel pick-up is located.
• Take samples from different points in the tank to determine where clear and bright fuel transitions to cloudy.
• Pump off and store the bottom fuel until the water naturally separates over time.

Testing for Contamination

To test fuel clarity, use this method: Diesel Fuel Contamination Test.
If the results are inconclusive, a lab test ($200–$400) may be required—contact us for recommendations.

Conclusion

Diesel fuel additives are a cost-effective way to improve engine performance in cold weather. They enhance cold flow without sacrificing power or performance and don’t reduce lubricity or cetane levels like kerosene.

However, excessive additive use can cause contamination issues. Based on our findings, the fuel was likely delivered with too much winter blend additive or was overdosed during treatment.

The post Troubleshooting Fuel Contamination Issues appeared first on Dieselcraft.

Dirty Fuel Might Be the Culprit!

Get your engines running at peak performance with Dieselcraft Fuel Polishing Machines! Our cutting-edge machines expertly eliminate water, sludge, and contaminants from your fuel, ensuring your diesel is always clean and ready for action. Whether you’re powering boats, trucks, or backup generators, Dieselcraft guarantees your fuel stays in prime condition—helping you save precious time, slash maintenance costs, and reduce fuel waste!

Boost Fuel Efficiency
Protect Your Engine’s Longevity
Lower Maintenance Costs

• Intuitive and High-Quality Design
• Perfect for Emergency Power Systems
• Proven Results in Eliminating Fuel Contamination

Don’t let dirty fuel compromise your performance. Choose Dieselcraft for reliable fuel solutions!
Learn more today! https://dieselcraft.com/portable-fuel-polishing/

The post Is Your Backup Generator Struggling Due to Diesel Engine Performance Issues? appeared first on Dieselcraft.

WARNING: Diesel Algae/Bacteria Alert!**

Is your fuel system at risk? Watch for these warning signs:

• Contamination: Check for sludge or dark layers at the bottom of the tank.
• Testing: Collect a fuel sample to analyze for harmful microbes using available kits.
• Filters: Look for blockages or slime on fuel filters.
• Professional Help: If contamination is suspected, consult a fuel quality testing service.

Don’t wait—act now to protect your fuel system!

Contact us for expert assistance:
https://dieselcraft.com/test-for-algae-bacteria-in-fuel/

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